May Lake Dam Reservoir Report

Last Updated: December 6, 2025

May Lake Dam, located in Cass, Missouri, was completed in 1976 and serves primarily for irrigation purposes.


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Summary

This private structure stands at a height of 20 feet and has a storage capacity of 193 acre-feet. The dam, constructed with earth materials, is classified as having a high hazard potential, although its condition assessment is currently listed as "Not Rated."

The dam also fulfills functions for fire protection, stock, small fish pond, recreation, and water supply. Situated on the TR-Mormon Fork river/stream, it covers a surface area of 18 acres and drains an area of 270 square miles. Despite being privately owned, May Lake Dam falls under the jurisdiction of the state of Missouri and is not state-regulated, inspected, or enforced.

Water resource and climate enthusiasts may find May Lake Dam a point of interest due to its significant role in irrigation and water supply within the region. With its high hazard potential and diverse purposes, this structure presents both challenges and opportunities for sustainable water management practices in the area.

Year Completed

1976

Dam Height

20

River Or Stream

TR-MORMON FORK

Primary Dam Type

Earth

Surface Area

18

Drainage Area

270

Nid Storage

193

Structural Height

20

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

20
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.